1. Field of the Invention
The present invention relates generally to vehicle steering mechanisms, and more particularly, pertains to an apparatus and method for steering a vehicle to follow a track or guideway.
2. Description of the Related Art
Vehicles adapted to travel on a track or a guideway typically employ at least one bogie attached to a vehicle frame. The bogie supports an axle having wheels with tires attached thereto. The vehicle further includes a steering linkage having a series of tie rods coupled to knuckles to turn the wheels with respect to the longitudinal axis of the vehicle frame. In a conventional arrangement, a first tie rod is connected to a steering mechanism and a first wheel while a second tie rod connects the first and seconds wheels. The vehicle is steered along a track or a pathway by a steering mechanism acting on the first tie rod. A typical steering mechanism is a rack and pinion arrangement.
While a conventional rack and pinion system enjoys a widespread use, there exist a number of limitations and disadvantages to this system. Depending on whether the vehicle is making a left or a right turn, current steering mechanisms result in asymmetrical steering angles. This presents unique problems for bi-directional vehicles. Due to the arrangement of the tie rods, turning the wheels at a particular angle in a first direction (i.e., left or right) requires a different steering angle input compared to turning the wheels at that same angle in a second direction (i.e., right or left, respectively). This non-linearity of steering input is intrinsic to the arrangement of the tie rods in the steering linkage system. An automatic guidance system which steers the vehicle along a predetermined track or guideway must account for the non-linearity resulting from the use of conventional steering mechanisms.
A design is needed which eliminates the bias associated with the non-linearity intrinsic to the steering linkage. There is a need in the art for a steering mechanism that provides symmetrical steering angles regardless of whether the vehicle is turning in a left or right direction.